Species-Specific Flash Patterns Track the Nocturnal Behavior of Sympatric Taiwanese Fireflies

It is highly challenging to evaluate the species’ content and behavior changes in wild fireflies, especially for a sympatric population. Here, the flash interval (FI) and flash duration (FD) of flying males from three sympatric species (Abscondita cerata, Luciola kagiana, and Luciola curtithorax) were investigated for their potentials in assessing species composition and nocturnal behaviors during the A. cerata mating season. Both FI and FD were quantified from the continuous flashes of adult fireflies (lasting 5–30 s) via spatiotemporal analyses of video recorded along the Genliao hiking trail in Taipei, Taiwan. Compared to FD patterns and flash colors, FI patterns exhibited the highest species specificity, making them a suitable reference for differentiating firefly species. Through the case study of a massive occurrence of A. cerata (21 April 2018), the species contents (~85% of the flying population) and active periods of a sympatric population comprising A. cerata and L. kagiana were successfully evaluated by FI pattern matching, as well as field specimen collections. Our study suggests that FI patterns may be a reliable species-specific luminous marker for monitoring the behavioral changes in a sympatric firefly population in the field, and has implication values for firefly conservation.

A geostationary lightning pseudo-observation generator utilizing low frequency ground-based lightning observations

Coincident Geostationary Lightning Mapper (GLM) and National Lightning Detection Network (NLDN) observations are used to build a generator of realistic lightning optical signal in the perspective to simulate Lightning Imager (LI) signal from European NLDN-like observations. Characteristics of GLM and NLDN flashes are used to train different machine learning (ML) models, that predict simulated pseudo-GLM flash extent, flash duration, and event number per flash (targets) from several NLDN flash characteristics. Comparing statistics of observed GLM targets and simulated pseudo-GLM targets, the most suitable ML-based target generators are identified. The simulated targets are then further processed to obtain pseudo-GLM events and flashes. In the perspective of lightning data assimilation, Flash Extent Density (FED) is derived from both observed and simulated GLM data. The best generators simulate accumulated hourly FED sums with a bias of 2% to the observation, while cumulated absolute differences remain of about 22 %. A visual comparison reveals that hourly simulated FED features local maxima at the similar geolocations as the FED derived from GLM observations. However, the simulated FED often exceeds the observed FED in regions of convective cores and high flash rates. The accumulated hourly area with FED>0 flashes per 5 km×5 km pixel simulated by some pseudo-GLM generators differs by only 7% to 8% from the observed values. The recommended generator uses a linear Support Vector Regressor (linSVR) to create pseudo-GLM FED. It provides the best balance between target simulation, hourly FED sum, and hourly electrified area.

Lightning Activity Observed by the FengYun-4A Lightning Mapping Imager

The Lightning Mapping Imager (LMI) onboard the geostationary meteorological satelliteFengYun-4A (FY-4A) detects both intra-cloud (IC) and cloud-to-ground (CG) lightning continuously during daytime and nighttime. This study examined, for the first time, the optical characteristics and distribution of the “Event,” “Group,” and “Flash” observed by the LMI in the whole LMI observation domain. The optical properties and spatial distribution of the LMI lightning were compared with those of the Lightning Imaging Sensor on the International Space Station (ISS-LIS) based on the dataset during 2018–2020. Due to the different spatial resolutions and detection efficiencies of these two lightning imagers, the number of ISS-LIS lightning was more than that of LMI lightning. The ISS-LIS Flash duration was also larger than that of the LMI Flash. The duration, radiance, and footprint of LMI lightning in different regions were analyzed in detail based on the LMI lightning dataset in 2019. The duration and radiance of the Flash were generally less than 50–500 ms and 200 Jm−2ster−1μm−1, respectively. The footprint of Flashes was distributed from 200 to 600 km2. The number of Groups per Flash was mostly less than five. Considering the spatial distribution and temporal variations in the LMI lightning compared with the ground-based Lightning Location Network in China (LLNC), it was found that the LMI Group number was close to the LLNC CG (Cloud-to-Ground) Event number. The maximum Flash density was found in the middle and lower south of the Yangtze River and Pearl River Delta region, respectively, while the lower values were in western China, where the mean radiance per Flash was greater. There was more LMI lightning during the nighttime than that during the daytime, indicating the higher detection efficiency of the LMI in the nighttime than in the daytime.

Light from a firefly at temperatures considerably higher and lower than normal

Bioluminescence emissions from a few species of fireflies have been studied at different temperatures. Variations in the flash-duration have been observed and interesting conclusions drawn in those studies. Here we investigate steady-state and pulsed emissions from male specimens of the Indian species Sclerotia substriata at temperatures considerably higher and lower than the ones at which they normally flash. When the temperature is raised to 34 °C, the peak wavelength gets red-shifted and the emitted pulses become the narrowest which broaden considerably thereafter for small increases in temperature; this probably indicates denaturation of the enzyme luciferase catalyzing the light-producing reaction. When the temperature is decreased to the region of 10.5–9 °C, the peak gets blue-shifted and the flash-duration increased abnormally with large fluctuation; this possibly implies cold denaturation of the luciferase. We conclude that the first or hot effect is very likely to be the reason of the species being dark-active on hot days, and the second or cold one is the probable reason for its disappearance at the onset of the winter. Our study makes the inference that these two happenings determine the temperature-tolerance, which plays a major role in the selection of the habitat for the firefly.

CN tower lightning flash characteristics based on high-speed imaging

The thesis emphasizes the analysis of fifty-eight flashes that struck the CN Tower during the last five years (2013-2017), based on video records of Phantom v5.0 digital high-speed imaging system, operating at 1 ms resolution. (A Sony HDR PJ790VB digital camera, operating at 16.67 ms resolution, provided a continuous recording of each CN Tower lightning storm.) It was observed that every recorded flash contained initial-stage current, confirming that all analyzed flashes were upward initiated. It was also observed that only 27 flashes out of the 58 contained return strokes. The number of strokes per flash varied between 1 and 9, with an average multiplicity of 2.16. The time variation of the channel luminosity of each flash was precisely analyzed for the characterization of flash components. A yearly statistical comparison regarding CN Tower lightning macroscopic (number of flashes, inter-flash times and flash durations) and microscopic (initial-stage current durations, number of the return strokes per flash, M-components and inter-stroke times) characteristics was conducted. The analysis of these extensive data (2013-2017) clearly showed that the 50% cumulative probability distribution (CPD) of flash duration in in 2017 was found to be the largest in comparison with other data (2013-2016). Whereas, the 50% CPD of inter-flash time duration in 2015 was the shortest. Furthermore, the 2014 data showed the longest 50% CPD of the initial-stage current duration as well as the inter-stroke time duration. In 2016, one flash was found to contain the highest number of return strokes. 2015 was distinguished by having the longest 50% CPD of the continuing current duration. It was also noted that two significantly major storms were captured during the nights of September 5, 2014 and September 4, 2017. During the storm of September 5, 2014, the CN Tower imaging systems recorded 13 flashes. The storm lasted for 111.4 minutes, resulting on average a flash to the tower every 9.28 minutes. Whereas, the September 4, 2017 storm continued for 49.35 minutes, producing 11 flashes for the tower every 4.9 minutes. The characterisation of CN Tower lightning is pivotal to the protection of tall structures against lightning hazards. It’s worth mentioning that flashes with longer flash duration, containing high number of return strokes and have shorter inter-stroke time durations pose severe threats to tall structures, electrical and communication systems

CN tower lightning flash characteristics based on high-speed imaging

The thesis emphasizes the analysis of fifty-eight flashes that struck the CN Tower during the last five years (2013-2017), based on video records of Phantom v5.0 digital high-speed imaging system, operating at 1 ms resolution. (A Sony HDR PJ790VB digital camera, operating at 16.67 ms resolution, provided a continuous recording of each CN Tower lightning storm.) It was observed that every recorded flash contained initial-stage current, confirming that all analyzed flashes were upward initiated. It was also observed that only 27 flashes out of the 58 contained return strokes. The number of strokes per flash varied between 1 and 9, with an average multiplicity of 2.16. The time variation of the channel luminosity of each flash was precisely analyzed for the characterization of flash components. A yearly statistical comparison regarding CN Tower lightning macroscopic (number of flashes, inter-flash times and flash durations) and microscopic (initial-stage current durations, number of the return strokes per flash, M-components and inter-stroke times) characteristics was conducted. The analysis of these extensive data (2013-2017) clearly showed that the 50% cumulative probability distribution (CPD) of flash duration in in 2017 was found to be the largest in comparison with other data (2013-2016). Whereas, the 50% CPD of inter-flash time duration in 2015 was the shortest. Furthermore, the 2014 data showed the longest 50% CPD of the initial-stage current duration as well as the inter-stroke time duration. In 2016, one flash was found to contain the highest number of return strokes. 2015 was distinguished by having the longest 50% CPD of the continuing current duration. It was also noted that two significantly major storms were captured during the nights of September 5, 2014 and September 4, 2017. During the storm of September 5, 2014, the CN Tower imaging systems recorded 13 flashes. The storm lasted for 111.4 minutes, resulting on average a flash to the tower every 9.28 minutes. Whereas, the September 4, 2017 storm continued for 49.35 minutes, producing 11 flashes for the tower every 4.9 minutes. The characterisation of CN Tower lightning is pivotal to the protection of tall structures against lightning hazards. It’s worth mentioning that flashes with longer flash duration, containing high number of return strokes and have shorter inter-stroke time durations pose severe threats to tall structures, electrical and communication systems

Observational study of tornadic cells that hit Corsica during the ADRIAN storm on the 29th October 2018

<p><span><span>The north-western Mediterranean basin often experiences thunderstorms with heavy precipitation, strong wind, lightning activity </span><span>and sometimes waterspouts/tornadoes</span><span>. One of the objectives of the EXAEDRE (EXploiting new Atmospheric Electricity Data for Research and the Environment) project is to better monitor the thunderstorms in this area through a better understanding of the physical processes that drive the dynamics, the microphysics and the electrical activity of the convective systems. </span><span>C</span><span>haracteristics </span><span>of the electrical activity </span><span>such as flash rate, charge layer </span><span>distribution</span><span> or flash polarity are good proxies for thunderstorm monitoring and good evidences of the storm severity.</span></span></p><p><span>The 29<sup>th</sup> October 2018, an intense trough developed over Mediterranean Sea between Balearic Islands and Corsica. This storm, called ADRIAN, produced several hazards (heavy precipitation, strong winds, intense lightning activity and hailstorm) in Corsica. Two tornadoes and one waterspout were observed in the morning at Porto Vecchio (EF2 tornado and waterspout) and Aleria (EF1 tornado), causing significant damages.</span></p><p><span>In this study, we take a look at electrical and microphysical characteristics of the two tornadic cells. </span><span>For that, observations of the LMA (Lightning Mapping Array) SAETTA network, deployed in Corsica, are used to document in 3D the total lightning activity. Complementary 2D lightning observations recorded by the French national lightning detection network METEORAGE are also investigated. We also use weather radar data from the Météo France network. A clustering algorithm is applied on both the lightning and radar data to identify and track the cells to document the evolution of several lightning-related and microphysical characteristics during the lifetime of each cell. We also applied a new method based on lightning leader velocity to automatically infer the vertical and horizontal structure of the electrical charge regions within each electrical cell.</span></p><p><span><span>We first introduce the different observations and methodologies applied here. Then the main electrical properties </span></span><span><span>of the tornadic cells </span></span><span><span>(e.g. flash duration, vertical flash extension, charge layer, flash type and polarity) </span></span><span><span>and microphysical characteristics </span></span><span><span>as well as their temporal evolution are presented. </span></span><span><span>Overall, t</span></span><span><span>h</span></span><span><span>e </span></span><span><span>studied electrical cells</span></span><span><span> produced few cloud-to-ground lightning </span></span><span><span>flashes</span></span><span> </span><span><span>p</span></span><span><span>redominantly of negative polarity. </span></span><span><span>The peaks of electrical activity occurred when tornadoes </span></span><span><span>hit the land and </span></span><span><span>these storms presented </span></span><span><span>all </span></span><span><span>an anomalous charge structure. </span></span></p>

Properties of the lightning flashes in North-western Mediterranean Sea as documented during the EXAEDRE project

<p><span>The EXAEDRE (EXploiting new Atmospheric Electricity Data for Research and the Environment) project aims at better understanding North-western Mediterranean Sea thunderstorms through coupled observational- and modelling-based studies with a dedicated focus on the lightning activity and its properties at flash, storm and regional scale.</span></p><p><span>In this work, the lightning activity is measured by the VHF Lightning Mapping Array (LMA) network SAETTA and the operational French lightning detection network Meteorage. SAETTA VHF sources are merged in flashes based on a DBSCAN algorithm (L2 SAETTA dataset). Meteorage strokes and pulses are then combined to SAETTA flashes based on temporal and pulse/stroke-dependent spatial criteria (L2b SAETTA-Meteorage dataset). Four categories of flashes can then be investigated: 1) CG L2b flashes with at least one CG stroke, 2) pure IC L2b flashes as detected by Meteorage with only IC pulses, 3) No-MTRG flashes which are only detected by SAETTA flashes with no concurrent Meteorage records, and 4) No-SAETTA flashes which were only reported by Meteorage with no concurrent SAETTA records.</span></p><p><span>Several lightning parameters have been investigated for the first three L2b flash categories listed above. It includes among others the flash duration, the vertical flash extension, the 2D horizontal flash extension</span><span>, </span><span>the </span><span>10/50/90 percent quantile of flash altitude, the flash trigger altitude, the stroke/pulse number per flash, and the flash vertical extension. Based on the L2b database </span><span>built from the SAETTA and Meteorage records of the entire year 2018, No-MTRG flashes have tendency to be rather small in terms of 2D flash extension or short in duration. They also statically exhibit a similar distribution of their </span><span>10/50/90 percent quantile of flash altitude. </span><span>CG L2b flashes exhibit mainly altitudes below 8 km while the majority of pure IC flashes show distinct distribution of </span><span>10/50/90 percent quantile </span><span>flash altitude. Three trigger altitude ranges, i.e. 4-5 km, 7-9 km, 11-12 km are found in the three studied categories. Finally, for the studied year, less +CG flashes occurred compared to the -CG flashes while CG flashes with more ground connections have the tendency to last longer and to be larger.</span></p><p><span>First we will introduce the instruments and the data. We will then present the different methodologies applied here to generate the L2b dataset with some typical lightning observations. We will then discuss on the characteristics of the different parameters listed above. </span></p>

The Study of Aviation Safe Incapacitating Device Based on LED Technology with a Smart-Illumination Sensor Unit

This paper deals with a design and implementation of optical defensive device for protection of aviation personnel. The design is built on the basic characteristics of human eyesight, illumination sensing of the environment, and microcontroller implementation for adaptation over sensed power, flash duration, and person distance. The aviation safe LED-based optical dazzler equipment (ASLODE) utilizes light emitting diode (LED) technology implemented with constant current regulators to control several modes of effects based on situational sensing. The temporarily incapacitating device can be extended by means of real-time illumination sensing to improve power efficiency and reach the highest level of safety. The smart pulse sets the flashing frequency from 8Hz for high-level light intensities and up to 20 Hz in low-level lighting conditions. Experimental results demonstrate the effectiveness of the ASLODE device over numerous experiments with controlled onboard aircraft scenarios that adapt the energy, flash rate, and processing to the sensed environmental illumination to meet aviation hygienic standards for people without eyesight defects.

Comparing lightning observations of the ground-based European lightning location system EUCLID and the space-based Lightning Imaging Sensor (LIS) on the International Space Station (ISS)

The Lightning Imaging Sensor (LIS) on the International Space Station (ISS), hereafter referred to as ISS-LIS, detects lightning from space by capturing the optical scattered light emitted from the top of the clouds. The ground-based European Cooperation for Lightning Detection (EUCLID) makes use of the low-frequency electromagnetic signals generated by lightning discharges to locate them accordingly. The objective of this work is to quantify the similarities and contrasts between these two distinct lightning detection technologies by comparing the EUCLID cloud-to-ground strokes and intracloud pulses to the ISS-LIS groups in addition to the correlation at the flash level. The analysis is based on the observations made between 1 March 2017 and 31 March 2019 within the EUCLID network and limited to 54∘ north. A Bayesian approach is adopted to determine the relative and absolute detection efficiencies (DEs) of each system. It is found that the EUCLID relative and absolute flash DE improves by approximately 10 % towards the center of the EUCLID network up to a value of 56.3 % and 69.0 %, respectively, compared to the averaged value over the full domain, inherent to the network geometry and sensor technology. In contrast, the relative and absolute ISS-LIS flash DE over the full domain is 48.4 % and 71.3 %, respectively, and is somewhat higher than the values obtained in the center of the EUCLID network. The behavior of the relative DE of each system in terms of the flash characteristics of the other reveals that the greater the value, the more likely the other system will detect the flash. For instance, when the ISS-LIS flash duration is smaller than or equal to 200 ms, the EUCLID relative flash DE drops below 50 %, whereas it increases up to 80 % for ISS-LIS flashes with a duration longer than 750 ms. Finally, the distribution of the diurnal DE indicates a higher DE for the ISS-LIS and a lower DE for EUCLID at night.